Using either the stow and assist button or if manual seats, sliding front row seats forward, there should be quite a bit of room to squeeze past a 2nd row forward facing seat.
Right now, I've got a pumpkin seat on passenger side (rear facing, of course), and a convertible seat forward facing on driver's side. With the pumpkin seat, you can easily just lift the seat out of the base then tilt the 2nd row to go behind, or just slip through in front and use the aisle. Forward facing seat is installed with the belt, so there is no tilting that one.
I really like the idea that Bluesfox mentions about stowing one of the 2nd row bucket seats. When I finally get to go on a road trip with wife, 2year old, and baby, I think that might be the configuration I use so that someone can sit next to the baby in the back if he needs comforting during the trip. It will depend on how much luggage is involved though.